On Tue, Dec 15, 2015 at 10:23 PM, Gernot Heiser <ger...@nicta.com.au> wrote:
> Nice!
>
> Just so I understand the setup: Does seL4 run in some super-privileged 
> (hypervisor) mode or do seL4 and RTEMS run at the same privilege level on 
> different cores? If it’s the latter, how is seL4 protected from the RTEMS 
> side?
>
elfloader is running in the most privilege RISC-V level (Machine
mode), but seL4 and RTEMS run on the same supervisor mode. RTEMS port
doesn't do any memory management, it runs as a single address space
process, hence, it can't alter its page-tables PTEs. seL4/application
allocates the page directory for RTEMS, and do the mapping, before
notifying the elfloader that it can boot RTEMS passing the address of
the page-table and the start physical address of the allocated memory
for RTEMS. elfloader (since it has the privilege) loads RTEMS from the
cpio archive, and sets the other core's register that points to the
allocate page-table, so RTEMS wouldn't be able to mess with memory
that's not allocated with it.

I actually wanted to run seL4 in Machine mode, but it only supports
base and bound protection (segments), and it's not yet supported by
the toolchain (binutils).

> Gernot
>
>> On 16 Dec 2015, at 9:13 , Hesham Almatary <heshamelmat...@gmail.com> wrote:
>>
>> Hi all,
>>
>> I got an RTEMS port working for RISC-V architecture along with seL4.
>> This depends on my earlier seL4 port for RISC-V.
>>
>> RTEMS runs with support of seL4 microkernel, and it runs in Supervisor
>> mode (on another core). seL4 application would allocate and map memory
>> for it from its untyped memory (userspace), before off-loading it to
>> another core.
>>
>> seL4 application that loads/runs RTEMS is pretty much the same as SOS.
>>
>> For more details (and instructions) about how to build/run the project, see
>> the github repo of the port [1], and/or this blog post [2]
>>
>> [1] https://github.com/heshamelmatary/rtems-riscv
>> [2] 
>> http://heshamelmatary.blogspot.co.uk/2015/12/rtems-port-for-risc-v-withwithout-sel4.html
>>
>> Cheers,
>> --
>> Hesham
>>
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-- 
Hesham

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